NOTE Grijalva-Chon et al.: Allozyme variability in Xiphias gladius 



593 



graphic areas. It is widely agreed that the absence 

 of genetic differences, as suggested by allozyme 

 analysis, cannot be attributed to genetic identity at 

 the DNA level (Utter et al., 1987). When differences 

 are evident from allozyme analysis, however, the 

 possibility of population differentiation exists to some 

 degree. According to our results, the genetic popula- 

 tion structure of swordfish in the North Pacific is 

 more complicated than previously shown by Chow 

 ( 1994 ) and Grijalva-Chon et al. ( 1994 ). From the fish- 

 ery resources management point of view, it is neces- 

 sary to corroborate the status of swordfish popula- 

 tions throughout the Pacific Ocean both with a DNA- 

 based character set and with allozyme analysis. 

 Moreover, future studies should include a sampling 

 strategy that analyzes temporal variation. 



Acknowledgments 



We thank R. de la Rosa-Pacheco (Camara Nacional 

 de la Industria Pesquera, Seccion Especializada en 

 Pesca de Pez Espada, Mexico), and R. Skillman and 

 J. Uchiyama (National Marine Fisheries Service, 

 Honolulu Laboratory) for their assistance in sam- 

 pling activities. We are very grateful for the valu- 

 able assistance of C. Jimenez in the laboratory. The 

 English in an early version of the manuscript was 

 substantially improved by S. Bullock and that ver- 

 sion was critically reviewed by J. Graves, B. Eitner, 

 and S. Chow. We thank the valuable contributions of 

 two anonymous referees. 



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